19 CFR § 10.609 - Transshipment of non-originating cotton or man-made fiber apparel goods.

(a) General. A good will not be considered eligible for preferential tariff treatment under an applicable TPL by reason of having undergone production that would enable the good to qualify for preferential tariff treatment if subsequent to that production the good:

(1) Undergoes production or any other operation outside the territories of the Parties, other than unloading, reloading, or any other operation necessary to preserve the good in good condition or to transport the good to the territory of a Party; or

(2) Does not remain under the control of customs authorities in the territory of a non-Party.

(b) Documentary evidence. An importer making a claim for preferential tariff treatment under an applicable TPL may be required to demonstrate, to CBP's satisfaction, that the requirements set forth in paragraph (a) of this section were met. An importer may demonstrate compliance with these requirements by submitting documentary evidence. Such evidence may include, but is not limited to, bills of lading, airway bills, packing lists, commercial invoices, receiving and inventory records, and customs entry and exit documents.